Három hete keresem azt a könyvet, de még mindig nem találom.

Három hete is a fixed time expression meaning for three weeks now in this sentence.

By contrast, három hét just means three weeks as a quantity. It does not by itself express the idea of for/since three weeks.

So:

három hét = three weeks
három hete = for three weeks now / three weeks ago, depending on context

In this sentence, because the verb is present tense, három hete means for three weeks now.

Hungarian often expresses time relationships without a separate preposition. English uses for, but Hungarian can build that meaning directly into the time expression.

So English says:

for three weeks

Hungarian says:

három hete

The for idea is already included in the form hete, so no extra word is needed.

Hungarian uses the present tense here because the action is still going on now.

So Három hete keresem... literally uses present tense, but in English the natural translation is often something like I have been looking for... for three weeks.

This is a very common difference between English and Hungarian:

Három hete keresem = I’ve been looking for it for three weeks
not literally just I look for it for three weeks

Hungarian does not need a special present perfect continuous form to express this idea.

Yes. This is an important point.

Három hete can mean either:

• for three weeks now, if the verb describes something ongoing, especially with present tense
• three weeks ago, if the verb refers to a completed event, usually with past tense

For example:

Három hete keresem. = I’ve been looking for it for three weeks.
Három hete vettem meg. = I bought it three weeks ago.

So the context and verb tense tell you which meaning is intended.

Because the object is definite: azt a könyvet means that book, a specific book.

Hungarian has two main types of verb conjugation:

• indefinite conjugation: used when there is no definite object
• definite conjugation: used when the object is definite

Here the object is specific, so Hungarian uses the definite form:

keresem = I am looking for it / that specific thing

Compare:

Keresek egy könyvet. = I’m looking for a book.
Keresem azt a könyvet. = I’m looking for that book.

That is why -em appears here.

In Hungarian, when a demonstrative like ez or az modifies a noun, the article is normally kept.

So Hungarian says:

az a könyv = that book

not just az könyv

In the accusative, this becomes:

azt a könyvet

Both parts are normal and required in standard Hungarian:

• azt = that, in accusative form
• a = the article
• könyvet = book, in accusative form

This double structure is one of the things that feels unusual to English speakers at first.

Because könyvet is the direct object, and Hungarian marks direct objects with the accusative ending -t.

The basic noun is:

könyv = book

As an object, it becomes:

könyvet = book, as the thing being looked for/found

The extra -e- is a linking vowel that makes pronunciation easier. So learners often think of it like this:

könyv + t becomes könyvet

You do not always get -et specifically; the exact form depends on the noun.

Because the object is already clear from the first clause: azt a könyvet.

So in the second clause, Hungarian can simply omit it:

de még mindig nem találom = but I still can’t find it

The verb találom is still in the definite conjugation, which fits the understood definite object. So even without repeating azt a könyvet, the sentence still clearly refers to that same specific book.

Még mindig means still.

It emphasizes that the situation continues up to now, often longer than expected.

So:

még mindig nem találom = I still can’t find it

You will often see még mindig in sentences about ongoing situations:

Még mindig várunk. = We’re still waiting.
Még mindig itt van. = He/She/It is still here.

It is stronger and clearer than just még in this kind of sentence.

In a neutral Hungarian clause, nem usually comes directly before the verb it negates.

So:

nem találom = I do not find it / I can’t find it

That is the normal placement for negation.

In this sentence:

de még mindig nem találom

the adverbial még mindig comes before the negative verb phrase, and nem stays right before találom.

The sentence is fairly natural and neutral.

Három hete at the front sets the time frame: for three weeks now. Then the sentence gives the action and object:

Három hete keresem azt a könyvet...

That is a very normal way to structure the sentence.

But Hungarian word order is flexible, and moving things changes emphasis. For example:

Azt a könyvet keresem három hete... puts more emphasis on that book
Három hete azt a könyvet keresem... can suggest contrast, as in that book in particular

So the given order sounds natural and unmarked.

Then the object would be indefinite, so the verbs would switch to the indefinite conjugation.

A natural version would be:

Három hete keresek egy könyvet, de még mindig nem találok egyet.

Notice the changes:

keresem → keresek
találom → találok

That happens because egy könyvet means a book, not a specific known book.

So this sentence is a good example of how definiteness affects Hungarian verbs.